Filter device and filter element provided therefor

ABSTRACT

A filter device, in particular for fluids polluted with admixtures of water, such as diesel oil, includes a filter housing ( 1 ) having a fluid inlet ( 43 ), a fluid outlet ( 44 ) and a filter element ( 9 ). During the filtering process, the fluid can flow through the filter medium ( 11 ) of the filter element from the unfiltered side ( 14 ) to the filtered side ( 13 ) of the filter medium and into its inner filter cavity ( 17 ). On at least one side of the filter medium ( 11 ), a water-separating system ( 23 ) has a separating region ( 25 ) for separated water. The water separating system is connected via at least one water opening ( 35 ) that is open toward the separating region ( 25 ) to a water collecting chamber ( 45 ). The filter element ( 9 ) has a passage ( 29 ) forming a fluid connection to the inner filter cavity ( 17 ) and can be connected to an element receptacle ( 47 ) of the filter housing ( 1 ). A fluid-conveying system ( 41 ) forms fluid paths separated from each other. The first fluid path ( 59/69 ) leads from the fluid inlet ( 43 ) of the housing ( 1 ) to the unfiltered side ( 14 ) of the filter element ( 9 ). The second fluid path ( 57 ) connects the respective water opening ( 35 ) to the water collecting chamber ( 45 ).

FIELD OF THE INVENTION

The invention relates to a filter device that is intended in particularfor fluids, such as diesel oil, contaminated with water impurities, andthat comprises a filter housing having a fluid inlet, a fluid outlet andat least one filter element accommodated therein. The filter medium ofthe filter element surrounds an inner filter cavity in the filtrationprocess. The fluid flows from the unfiltered side to the filtered side.On at least one side of the filter medium, a water separation device hasa separating region for separated water connected to a water collectingspace via at least one water passage that is open to the separatingregion. The filter element has a passage forming a fluid connection tothe inner filter cavity and is securable on an element retainer of thefilter housing. Furthermore, the invention relates to a filter elementintended for use in such a filter device.

BACKGROUND OF THE INVENTION

Filter devices of the aforementioned type are known from the prior art.Such filter devices are typically used in fuel systems for internalcombustion engines to protect sensitive components, in particular theinjection systems, against degradation due to the water contententrained in the fuel. In this case, separation of the water contententrained in the fuel can be effected by a coagulation process duringwhich water droplets are formed on the filter medium. These waterdroplets can flow out of the separation space, formed in the filterelement, to the water collecting space.

To ensure the operational reliability of the systems located downstreamof the filter, avoiding system contamination by dirt is critical in theprocesses of changing the filter element as necessary over the servicelife. The fluid connection between the filtered side of the filterelement and the fluid outlet of the housing is interrupted when the endcap of the used filter element is decoupled from the element retainer.Dirt that has accumulated on the used filter element must be preventedfrom falling off. A separate reliable conveyance of the fluid by thewater that forms is also desirable to increase operational reliability.

SUMMARY OF THE INVENTION

An object of the invention is to provide an improved filter device ofthe type under consideration, whose construction ensures a maximum ofoperational reliability and reduces the risk of contamination duringchanging processes, in particular at the fluid outlet of the housing.

This object is basically achieved according to the invention by a filterdevice having a fluid-conducting device in which fluid paths separatedfrom one another formed, with a first fluid path leading from the fluidinlet of the housing to the unfiltered side of the filter element and asecond fluid path connecting the water passage to the water collectingspace. In this way, a reliable separation of the fluid paths underconsideration via the fluid-conducting device is created. Even when aused filter element is removed and replaced by a new element, nocontamination of the system occurs by dirt accumulated on the usedfilter element falling off in the direction of the filtered side.Rather, this dirt remains on the unfiltered side. An inadvertentintroduction of water either to the filtered side or to the unfilteredside is not possible either.

Compared to known filter devices of this type, in which in thefiltration process flow takes place through the filter medium of thefilter element from its outer unfiltered side to the inner filter cavityforming the filtered side, in one advantageous embodiment of theinvention, the fluid-conducting device induces a kind of flow reversal.Flow then takes place through the filter element preferably from theinner filter cavity to the outside. This reverse flow substantiallyimproves the situation during the process of changing the filter. Whenflow takes place through the filter element from the inside to theoutside, the unfiltered side is located in the inner filter cavity. Dirtparticles, accumulated on the unfiltered side that might fall off whenthe filter element is removed, remain in the separated region of theunfiltered-side fluid path. Also, the fluid outlet that discharges onthe outside of the filter medium that forms the filtered side is locatedoutside the “endangered” region. The risk of fouling of the systemdownstream of the fluid outlet is thus effectively prevented.

In an especially advantageous manner, the unfiltered side is formed bythe inner filter cavity of the filter element, and the water separationdevice with its water passage that is open toward the separating regionare components of the filter element.

The water collecting space is preferably arranged to adjoin the filterhousing such that at the lowest point of the filter housing, with theelement retainer of the filter housing being located above the watercollecting space.

In exemplary embodiments, the filter element on its lower end has an endcap with the passage leading into the filter cavity and with at leastone water passage. The fluid-conducting device can then be brought intoa sealed fluid connection to the end cap. Mechanically, this structureresults in a simple structure.

Especially advantageously, the fluid-conducting device for forming theseparate fluid paths has an adapter part designed as a connectingelement via which the end cap of the filter element can be secured onthe element retainer. The end cap thus can be designed as a disposablecomponent to be changed together with the filter element in a simple,economically producible construction. The fluid-conducting deviceforming the separate fluid paths can form its own component separatefrom the end cap in the form of the adapter part.

In advantageous exemplary embodiments, the preferably circular end capon its peripheral edge has an annular body forming inner annular jacketsurfaces separated from one another and extending in the axialdirection. One of the jacket surfaces adjoins a hydrophobic screen thatsurrounds the outside of the filter medium at a radial distance formingthe separating region. Another of the jacket surfaces forms a sealingsurface for the fluid-tight contact of a peripheral edge part of theadapter part.

With respect to the configuration of the end cap, preferably the end capfor formation of the passage has a pipe section extending from the endcap bottom forming the support for the filter medium and defining themain plane of the end cap. This pipe section extends axially upward intothe filter cavity and axially downward for a sealed engagement with aninner pipe located in the adapter part and, as part of the fluid path,being fluid-connected to the fluid inlet of the housing.

In especially advantageous exemplary embodiments, the inner pipe of theadapter part is surrounded by a sleeve body that is open toward thewater collecting space on the lower end facing away from the end cap andthat surrounds the inner pipe at a distance by which a water channel isformed as part of the second fluid path.

Furthermore, the adapter part can advantageously be made such that thesleeve body of the adapter part on its end facing the end cap has a flatring washer that is continuous without interruption up to its peripheraledge part and that can be moved into sealed contact with the assignedannular jacket surface of the end cap. In the operating position, theflat ring washer extends along the end cap bottom at a distance by whichthe water channel of the sleeve body is continued up to the respectivewater passage formed in the end cap bottom. The adapter part used as afluid-conducting device, together with the underside of the end capbottom, thus forms the part of the second fluid path via which the watercollected in the separation space drains out, which part leads to therespective water passage.

The element retainer can advantageously have a pipe connector that formsthe connection between a water collecting space and the main part of thehousing accommodating the filter element. In the connector, the sleevebody of the adapter part can be accommodated to secure the pertinentfilter element via its end cap that is in sealing connection to theadapter part in the housing.

For its function as a fluid-conducting device, the adapter part canadvantageously be designed such that the sleeve body on its outside forcontact with the inside of the pipe connector of the element retainerhas two radially projecting annular parts arranged at an axial distancefrom one another. An annulus is then formed between the outside of thesleeve body and the inside of the pipe connector of the elementretainer, with a feed channel leading to the fluid inlet of the housingas part of the first fluid path discharging into the annulus.

For this fluid path to extend from the inner pipe to the fluid inlet, aconnecting channel branches off from the inner pipe of the adapter part,discharges into the annulus on the outside of the sleeve body andcontinues the first fluid path to the fluid inlet of the housing.

With respect to the sealing between the end cap of the filter element,adapter part and element retainer, O-rings can seal the annular parts ofthe sleeve body on the pipe connector of the element retainer, the pipebody of the end cap on the inner pipe of the adapter part, and the edgepart of the ring washer of the adapter part on the annular jacketsurface of the end cap.

The sealing of the outside of the sleeve body of the adapter partrelative to the inside wall of the element retainer affords theadditional advantage that the otherwise conventional sealing of theouter periphery of the end cap relative to the inside of the housing iseliminated. Instead, the sealing between the filtered side and theunfiltered side is affected with much smaller seal diameter. Reducedinstallation forces and thus a simplification result during theinstallation and removal of filter elements.

The subject matter of the invention is also a filter element intendedfor use in the filter device according to the invention.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses a preferredembodiment

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings that form a part of this disclosure:

FIG. 1 is a side elevational view in section of a filter deviceaccording to an exemplary embodiment of the invention; and

FIG. 2 is an enlarged, partial perspective view of only the region ofthe filter device of FIG. 1 that borders the fluid-conducting device.

DETAILED DESCRIPTION OF THE DRAWINGS

The device has a filter housing 1 with a hollow cylindrical main part 3and a bottom part 5 that adjoins the housing bottom side. On the upperend, a housing cover 7 that can be removed for installing and removing afilter element 9 is screwed to the main part 3. Between the outside ofthe filter element 9 held in the housing 1 and the inside wall of thehousing 1, an intermediate space forms the filtered side 13 in thefiltration process. A fluid outlet 44 leads from the filtered side 13out of the housing 1 for the drainage of the cleaned fluid. The filtermedium 11 of the filter element 9 is formed by a filter mat shaped intoa hollow cylinder and surrounding the fluid-permeable support pipe 15forming an inner filter cavity 17 that, in the filtration process, formsthe unfiltered side 14 to which the fluid to be cleaned can be supplied.The fluid flows through the filter medium 11 from the inside to theoutside in the filtration process.

The ends of the filter element have, in the conventional manner, endcaps 19 and 21 that form enclosures for the filter medium 11 and thesupport pipe 15. The end caps 19, 21 moreover form an enclosure for ahydrophobic screen 23 in the form of an hollow cylinder that surroundsthe outside of the filter medium 11 at a distance. A separating region25 in the form of a separating space is then formed between thehydrophobic screen 23 and the filter medium 11. To effect waterseparation, as is conventional in these fuel filters, the filter medium11 acts to coagulate the water entrained by the fuel so that water indroplet form precipitates out of the fluid and sinks down in theseparation space 25 since the screen 23 is impermeable to coagulatedwater droplets.

The lower end cap 21 secures the filter element 9 in the operatingposition in the housing 1 and is designed such that it interacts with afluid-conducting device for filtration operation. For this purpose, theend cap 21 has a pipe section 27 that forms a passage 29 for the inflowof fluid to the inner filter cavity 17. The pipe section 27 extends fromthe end cap bottom 31 that forms a flat support surface for the loweredge of the filter medium 11, both axially upward into the filter cavity17 and downward axially from the end cap bottom 31. As an outerperipheral edge, the end cap bottom 31 has an annular body 33. Gaps inthe end cap bottom 39 are aligned to the separating region 25 and formwater passages 35 for the exit of water from the separation space 25.The annular body 33 of the end cap 21 is shaped such that above andbelow the end cap bottom 31, annular jacket surfaces 37 are formed. Thefirst or upper annular jacket surface adjoins the hydrophobic screen 23.The second or lower annular jacket surface 37 forms a sealing surfacefor the interaction with a peripheral edge part 39 of an adapter part 41used as the fluid-conducting device.

The adapter part 41, in its operation as a fluid-conducting device,forms fluid paths that are separated from one another. A first fluidpath leads from the fluid inlet 43 of the housing 1 via the passage 29to the filter cavity 17 forming the unfiltered side 14. The second fluidpath leads via the water passages 35 out of the separating region 25 asfar as the water collecting space 45 in the bottom part 5 of thehousing. Instead of an independent adapter part 41, its connectiongeometry can also be an integral component of the lower end cap 21 ofthe filter element 9.

In this example, the element retainer 47, on which the filter element 9can be secured via the adapter part 41 used as a connecting orintermediate element, has a pipe connector 49 forming the singleconnection between the main housing part 3 that holds the filter element9 and the water collecting space 45. The adapter part 41 has a sleevebody 51 that can be accommodated in the pipe connector 49. On its lowerend 53, sleeve body 51 is open to the water collecting space 45. On itstop end, sleeve body 51 undergoes transition into a ring washer 55 thatextends in a radial plane and that, on its peripheral edge, forms theedge part 39 projecting axially upward and sealed to the inner annularjacket surface 37 of the annular body 33 of the end cap 21. In this way,proceeding from the water passages 35, a water channel 57 is formedbetween the end cap bottom 31 and the washer 55 of the adapter part 41,which channel continues along the inside of the sleeve body 51 as far asthe water collecting space 45 and forms the second fluid path.

For the formation of the first fluid path from the fluid inlet 43 of thehousing 1 via the adapter part 41 and the passage 29 of the end cap 31into the inner filter cavity 17, the adapter part 41 has an inner pipe59 extending concentrically within the sleeve body 51 at a distance fromits inside wall. A space then remains open for the water channel 55 onthe outside of the inner pipe 59. The pipe section 27 with the passage29 sealingly engages the inner pipe 59.

The sleeve body 51, in the vicinity of its lower end and in the vicinityof the upper ring washer 55, has radially projecting annular parts 61and 63, respectively, on which sealing takes place relative to theinside wall of the pipe connector 49 of the element retainer 47. Theradially projecting annular parts 61, 63 between the pipe connector 49and the sleeve body 51 form an annulus 65, from which a feed channel(not visible in the drawings), leads to the fluid inlet 43 that formsthe inlet part of the first fluid path. For the continuation of thisfluid path via the inner pipe 49 of the adapter part 41 as far as thefilter cavity 17 forming the unfiltered side 14, a connecting channel 69branches off from the closed end 67 of the inner pipe 59 and leads intothe annulus 65. The first fluid path then continues from the fluid inlet43, the annulus 65, and the connecting channel 69 of the inner pipe 49as far as to the passage 29 of the end cap 21. The inner pipe 59 isconnected preferably integrally to the sleeve body 51 via the connectingchannel 69 and/or via connecting bridges (not detailed).

As is apparent from the figures, the sealings of the annular parts 61,63 of the sleeve body 51 take place on the pipe connector 49 of theelement retainer 47. Sealings of the pipe section 27 of the end cap 21take place on the inner pipe 59 of the adapter part 41. Sealings of theedge part 49 of the ring washer 55 of the adapter part 41 take place onthe annular jacket surface 37 of the end cap 21. Each of these sealingsis by O-rings 71. In the sealing formed in this way, seals for the outerperiphery of the end cap 21 of the filter element 9 relative to theinside of the housing 1 are unnecessary.

The filter element 9 has the filter medium 11 surrounding the innerfilter cavity 17 through which the fluid to be filtered flows for thefiltration process. On the outer peripheral side of the filter medium 11the water separation device 23 and the separating region 25 forseparated water is located. The separating region 25 has at least onewater passage 35. Passage 29 forms the fluid connection to the innerfilter cavity 17 of the filter element 9. The water passage 35 isseparated from the passage 29 within the filter element 9 by theadapter-shaped fluid-conducting device 41.

On the lower end of the filter element 9, the end cap 21 accommodatesthe filter medium 11 and has the passage 29 that leads into the innerfilter cavity 17 and the respective water passage 35, with the end cap21 being fluid-connected in a sealed manner to the fluid-conductingdevice 41. When the filter element 9 completed in this way is removedfrom the filter housing 1 after unscrewing the upper housing cover 7,for example, to replace a used filter element with a new element, theparticulate dirt settled on the inside of the filter medium 11 as wellas possible residues of unfiltered fluid remain on the unfiltered side14 of the filtration assembly. Separated water that is still present inthe separating region 25 travels via the respective passage site 35further in the direction of the water collecting space 45 and does notinadvertently reach the unfiltered side 14 nor the filtered side 13.

The water collecting space 45 located on the bottom side of the filterhousing 1 is surrounded by a collection housing that can be screwed ontothe filter housing 1 from underneath. The collection housing ispreferably of a transparent, cup-shaped plastic. As is especiallyapparent from FIG. 1, on the bottom side of the collection housing, atleast one water removal device or drain, for example, in the form of aconventional drain screw is provided. When the water collecting space 45in the collection housing is correspondingly filled, the water can bedischarged in this way from the device via the respective drain screw.After the installation of the appropriate new filter element 9 andemptying of the collection housing tank at least at maximum fill levelof the water collecting space 45, the filter device is then availableagain for further filtration operation.

While one embodiment has been chosen to illustrate the invention, itwill be understood by those skilled in the art that various changes andmodifications can be made therein without departing from the scope ofthe invention as defined in the appended claims.

What is claimed is:
 1. A filter device, comprising: a filter housinghaving a fluid inlet, a fluid outlet, a water collecting space and anelement retainer; at least one filter element in said filter housing,said filter element having a filter medium surrounding an inner filtercavity and having an unfiltered side and a filtered side, said filterelement having an end cap with a passage forming a fluid connection tosaid inner cavity, said end cap being releasably securable on saidelement retainer; a water separation device with a separating region forseparated water in said filter housing; and a fluid conducting devicehaving first and second fluid paths therein separated from one another,said first fluid path connecting said fluid inlet to said unfilteredside of said filter element, said second fluid path connecting a waterpassage connected to said separating region to said water collectingspace, said fluid connecting device including an adapter part providinga connecting part securing said filter element via said end cap thereofon said element retainer, said adapter part having an inner pipeextending concentrically within a sleeve body at a distance from aninside wall of said sleeve body providing a space between said innerpipe and said sleeve body forming an open water channel on an outside ofsaid inner pipe to form part of said second path.
 2. A filter deviceaccording to claim 1 wherein said unfiltered side is on an inner surfaceof said filter medium facing said inner filter cavity; and said filteredside is on an outer surface of said filter medium facing said separatingregion.
 3. A filter device according to claim 2 wherein said waterseparation device and said water passage are components of said filterelement.
 4. A filter device according to claim 2 wherein said watercollecting space is at a lowest point of and adjoins said filterhousing; and said element retainer is located above said watercollecting space.
 5. A filter device according to claim 2 wherein saidend cap receives said filter medium; said water passage is in said endcap; and said fluid conducting device has a sealed fluid connection tosaid end cap.
 6. A filter device according to claim 2 wherein said endcap comprises a circular peripheral edge and an annular body on saidperipheral edge, said annular body having first and second inner annularjacket surfaces separated from one another and extending in an axialdirection, said first inner annular jacket surface adjoining ahydrophobic screen surrounding said outer surface of said filter mediumat a radial distance forming said separating region, said second innerannular jacket surface forming a sealing surface in fluid-tight contactwith a peripheral edge part of said adapter part.
 7. A filter deviceaccording to claim 6 wherein said end cap comprises a pipe sectionforming said passage of said end cap and extending from an end capbottom axially upwardly into said filter cavity and axially downwardlyto sealingly engage said inner pipe located in said adapter part, saidend cap bottom forming a support for said filter medium and defining amain plane of said end cap, said pipe section and said inner pipeforming a portion of said first fluid path.
 8. A filter device accordingto claim 7 wherein said sleeve body is open toward said water collectingspace on a lower end thereof facing away from said end cap.
 9. A filterdevice according to claim 6 wherein said sleeve body comprises a flatring washer on a sleeve body end facing said end cap, said flat ringwasher being continuous without interruption to a peripheral edge partthereof in sealed contact with said second inner annular jacket surfaceof said end cap and extending along said end cap bottom at a distancetherefrom forming a water channel portion of said second fluid path fromsaid water passage that is in said end cap.
 10. A filter deviceaccording to claim 9 wherein said element retainer comprises a pipeconnector connecting said water collecting space and a main part of saidfilter housing receiving said filter element, said sleeve body beingreceived in said pipe connector to secure and seal said end cap to saidadapter part.
 11. A filter device according to claim 10 wherein saidsleeve body comprises first and second radially outwardly projectingannular parts arranged at an axial distance from one another on anoutside surface of said sleeve body, said radially outwardly projectingannular parts contacting an inside surface of said pipe connector anddefining an annulus between said outer surface of said sleeve body, saidinside surface of said pipe connector and said first and second radiallyoutwardly projecting annular parts; and a feed channel connects saidfluid inlet and said annulus forming a part of said first fluid path.12. A filter device according to claim 11 wherein a connecting channelconnects said inner pipe of said adapter part and said annulus.
 13. Afilter device according to claim 11 wherein O-rings extend and formseals between said radially outwardly projecting annular parts of saidsleeve body and said inside surface of said pipe connector of saidelement retainer, between said pipe section of said end cap and saidinner pipe of said adapter part, and between said edge part of said flatring washer of said adapter part and said second annular jacket surfaceof said end cap.
 14. A filter element for a filter device, comprising: afilter medium surrounding an inner filter cavity, having an unfilteredside on an inner surface of said filter medium and having a filteredside on an outer surface of said filter medium; a water separationdevice spaced radially outwardly on said outer surface of said filtermedium; a separating region between said water separation device andsaid filter medium; at least one water passage extending from saidseparating region; a fluid passage extending from said inner filtercavity of said filter medium and being separated from said water passagemaintaining separation of flows in said fluid passage and said waterpassage; an end cap on a lower end of said filter medium and containssaid fluid passage and said water passage, said end cap being sealableto a fluid conducting device in a filter housing; and a fluid conductingdevice coupled to said end cap and has first and second fluid pathstherein separated from one another, said first fluid path connecting afluid inlet to said unfiltered side of said filter element, said secondfluid path connecting said water passage connected to said separatingregion to a water collecting space, said fluid connecting deviceincluding an adapter part providing a connecting part securing said endcap on said element retainer, said adapter part having an inner pipeextending concentrically within a sleeve body at a distance from aninside wall of said sleeve body providing a space between said innerpipe and said sleeve body forming an open water channel on an outside ofsaid inner pipe to form part of said second path.
 15. A filter elementaccording to claim 14 wherein said end cap comprises a connectingelement connectable to the fluid-conducting device in the filterhousing.
 16. A filter element according to claim 15 wherein said end capcomprises a circular peripheral edge and an annular body on saidperipheral edge, said annular body having first and second inner annularjacket surfaces separated from one another and extending in an axialdirection, said first inner annular jacket surface adjoining ahydrophobic screen surrounding said outer surface of said filter mediumat a radial distance forming said separating region, said second innerannular jacket surface being sealable in fluid-tight contact with aperipheral edge part of an adapter part in the filter housing.
 17. Afilter element according to claim 16 wherein said end cap comprises apipe section forming said fluid passage of said end cap and extendingfrom an end cap bottom axially upwardly into said filter cavity andaxially downwardly to sealingly engage an inner pipe located in theadapter part, said end cap bottom forming a support for said filtermedium and defining a main plane of said end cap.